RF plasma method

ABSTRACT

An RF plasma etch reactor having an etch chamber with electrically conductive walls and a protective layer forming the portion of the walls facing the interior of the chamber. The protective layer prevents sputtering of material from the chamber walls by a plasma formed within the chamber. The etch reactor also has an inductive coil antenna disposed within the etch chamber which is used to generate the plasma by inductive coupling. Like the chamber walls, the inductive coil antenna is constructed to prevent sputtering of the material making up the antenna by the plasma. The coil antenna can take on any configuration (e.g. location, shape, orientation) that is necessary to achieve a desired power deposition pattern within the chamber. Examples of potential coil antenna configurations for achieving the desired power deposition pattern include constructing the coil antenna with a unitary or a segmented structure. The segmented structure involves the use of at least two coil segments wherein each segment is electrically isolated from the other segments and connected to a separate RF power signal. The unitary coil antenna or each of the coil segments can have a planar shape, a cylindrical shape, a truncated conical shape, a dome shape, or any combination thereof. The conductive walls are electrically grounded to serve as an electrical ground (i.e. anode) for a workpiece-supporting pedestal which is connected to a source of RF power to create a bias voltage at the surface of the workpiece.

This is a divisional of application Ser. No. 08/869,798, filed Jun. 5,1997 issued as U.S. Pat. No. 6,071,372 on Jun. 6, 2000.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to an RF plasma etch reactor, and moreparticularly to such a reactor employing an internal inductive coilantenna and electrically conductive chamber walls.

2. Background Art

A typical inductively coupled plasma etch reactor of the type currentlyavailable is depicted in FIG. 1. This reactor has a vacuum chamber 10surrounded by an inductive coil 12. A workpiece 14, usually asemiconductor wafer, is supported inside the chamber 10 on a pedestal16. An inductive coil antenna 12 is wound around the outside of thechamber 10 and connected to a radio frequency (RF) power generator 18through an impedance matching network 20 to provide RF power into thechamber. In addition, a bias RF power generator 22 and associatedimpedance matching circuit 24 is connected to the pedestal 16 and usedto impose a bias on the workpiece 14. The chamber walls 30 are composedof an electrically insulating material, typically quartz or ceramic, soas to minimize attenuation of the RF power coupled into the chamber 10.Underlying the insulative chamber walls 30 and surrounding the pedestal16 is a portion 34 of the chamber constructed of a conductive material.This conductive portion 34 is electrically grounded and serves as theground for the RF power supplied to the pedestal 16. There are alsocooling channels 32 formed within the conductive portion 34. Coolantfluid is pumped through the channels 32 to transfer heat away from theinterior of the chamber 10 so that the chamber temperature can bemaintained at a particular level desired for the etch process beingperformed. The exterior of the chamber walls 30 are also cooled for thesame reason. However, as insulative materials such as quartz and ceramiccannot be easily formed with internal cooling channels, the exteriorsurface of the walls 30 are cooled, typically by forced air convectionmethods. Etchant gas is introduced into the chamber 10 through gasinjection ports 26. A vacuum pump 28 evacuates the chamber 10 to adesired chamber pressure.

In operation, an etchant gas is introduced into the interior of thechamber 10 and RF power inductively coupled from the coil 12 generates aplasma within the chamber. The plasma produces etchant species (e.g.ions and radicals) from the etchant gas which are used to etch theworkpiece 14. A key component of anisotropic etching processes is thebombardment of the workpiece 14 with ions produced in the plasma. Theenergy and directionality exhibited by the ions and their density withinthe plasma are important factors which, to a large part, determine thequality of the resulting etched workpiece 14. These factorssubstantially determine etch uniformity, etch rate, photoresistselectivity, the straightness of the etch profile, and the smoothness ofetch feature sidewalls. For example, a high plasma ion energy at thesurface of the workpiece 14 is desirable so as to prevent isotropicetching and to maximize the etching rate. However, ion energy which istoo high will produce poor etching results, such as high photoresistloss, and can cause damage to the devices being formed on the workpiece14. Therefore, the plasma ion energy is ideally kept relatively near butbelow a threshold at which the etch quality begins to deterioratesignificantly and/or where device damage becomes unacceptable.Similarly, a high plasma ion density is desirable so as to maintain ahigh etch rate. Essentially, the more ions there are, regardless oftheir energy, the faster the workpiece 14 is etched.

In the inductively coupled reactor of FIG. 1, the plasma ion density issubstantially controlled by the amount of RF power coupled into thechamber via the coil 12. For the most part, the more power coupled, thehigher the plasma ion density. Thus, in most cases, the plasma iondensity can be held to a desired level by selecting the appropriateamount of RF power to be supplied by the RF power generator 18 to thecoil 12. The RF power coupled into the chamber by the coil 12, however,does not significantly affect the plasma ion energy at the surface ofthe workpiece 14. Control of the ion energy at the surface of theworkpiece is conventionally accomplished by capacitively coupling RFpower into the chamber via the to the pedestal 16 using the bias RFpower generator 22. Ideally, the bias power supplied to the pedestal 16will not significantly affect the ion density produced in the chamber10, thereby decoupling the control of ion density and ion energy.

The plasma ion energy controlled by the bias RF power applied to thepedestal 16 is, however, affected by the ratio of the surface area ofthe pedestal to the surface area of the grounded portion 34 of thechamber. The pedestal 16 acts as the cathode and the grounded portion 34serves as the anode to form a capacitively coupled circuit. Since themajority of the interior surface of the chamber 10 is formed by theinsulative chamber walls 30 to maximize the inductive coupling of powerinto the chamber from the coil 12, the surface area associated with thegrounded portion 34 is necessarily limited, and typically not too muchlarger than that of the pedestal 16. An ion energy control problemresults because the surface areas of the grounded portion 34 and thepedestal 16 are too close in size in a conventional inductively coupledetch reactor. When the surface area of the pedestal 16 is less than thatof the grounded portion 34, the average voltage (often referred to asthe DC bias voltage) at the surface of the workpiece 14 is negative.This average negative voltage is employed to draw the positively chargedions from the plasma to the workpiece 14. However, if the surface areaof the pedestal 16 is only slightly smaller than the surface area of thegrounded portion (as is typically the case in a conventional inductivelycoupled plasma etch reactor), the average negative voltage at thesurface of the workpiece 14 is relatively small. This small bias voltageresults in a weak attracting force and so a relatively low average ionenergy. A higher negative bias voltage value than can typically beobtained using a conventional inductively coupled plasma etch reactor isnecessary to optimize the plasma ion energy so as to ensure the maximumetch rate and no significant damage to the devices being formed on theworkpiece 14. Ideally, the surface area of the grounded portion 34 wouldbe sufficiently large in comparison with that of the pedestal 16 so asto produce the maximum possible negative average voltage at the surfaceof the workpiece 14, i.e. one half the peak to peak voltage.

The previously-described inductively coupled etch reactor has in thepast been used to etch aluminum from the surface of the workpiece 14.This etching process produced byproducts comprising mostly aluminumchlorides (AlCl_(x)) and fragments of photoresist which tend to depositon the walls of the reactor chamber 10. The byproducts of an aluminumetch have no significant effect on the plasma characteristics (e.g.plasma ion density and energy) because they are almost totallynon-conductive. However, it is also desirable to etch other metals fromthe surface of a workpiece 14, such as copper (Cu), platinum (Pt),tantalum (Ta), rhodium (Rh), and titanium (Ti), among others. Etchingthese metals presents a problem when using the conventional etch reactorof FIG. 1 because the etching by-products of these metals tend to beconductive. Thus, a conductive coating forms on the chamber walls. Thisconductive coating has the effect of attenuating the RF power coupledinto the chamber by the coil 12. The coil 12 produces a magnetic fieldwhich results in power being coupled into the chamber. When the interiorsurface of the chamber under the coil 12 is coated with a conductivematerial, eddy currents are produced in this material, therebyattenuating the magnetic field to some extent and reducing the amount ofpower coupled into the interior of the chamber 10. As the conductivecoating builds in thickness over successive etch processes, theattenuation progressively increases and the power coupling into theplasma progressively decreases. It has been found that a 10 to 20percent decrease in power coupled into the plasma occurs afterprocessing 100 workpieces. In addition, the conductive coating canelectrically couple to the grounded anode portion 34 of the chamber,thereby effectively increasing the anode area. This increase in anodearea in turn tends to increase the previously mentioned negative DC biasvoltage. The change in the bias voltage due to the altered effectiveanode area results in an unexpected increase in the capacitive couplingof RF power from the pedestal.

The progressive reduction of inductively coupled RF power and increasein capacitively coupled RF power have detrimental effects on the etchingprocess. For example, the plasma ion density is lowered due to thedecrease in inductively coupled RF power and the plasma ion energy isincreased due to the increase in capacitively coupled power. As the RFpower levels are typically set prior to the etching process to optimizeplasma ion density and energy, any change could have an undesirableimpact on etch quality. The changes in power coupling caused byconductive etch by-products coating the chamber 10 also affect otheretch process parameters and plasma characteristics, as well. Forinstance, the photoresist selectivity is lowered, etch stop depths arereduced, and ion current/energy distribution and the etch rate areadversely affected. These changed parameters and characteristics resultin different, and often unacceptable workpiece etch characteristics(such as poor photoresist selectivity, poor etch rate uniformity or etchrate shift, and device damage). It has been found that even after onlytwo or three workpieces 14 have been etched, unwanted changes in theetch profile can be observed. In addition to the detrimental effects onthe etch process parameters and plasma characteristics, it has also beenfound that the reduced inductive coupling of RF power into the chamber10 causes problems with igniting and maintaining a plasma.

Of course, the decrease in inductively coupled power could becompensated for by increasing the RF power supplied to the coil 12.Similarly, the increase in capacitively coupled power can be compensatedfor by decreasing the RF power supplied to the pedestal 16. In addition,the chamber walls can be cleaned more often than would typically benecessary when etching materials producing non-conductive by-productssuch as aluminum. However, these types of work-arounds are generallyimpractical. A user of an etch reactor typically prefers to set therespective RF power levels in accordance with a so-called “recipe”supplied by the reactor's manufacturer. Having to deviate from therecipe to compensate for the conductive deposits would be unacceptableto most users. Further, it is believed that the aforementioneddetrimental effects will be unpredictable, and therefore, the requiredchanges in the RF power settings needed to compensate could not bepredetermined. Thus, unless the user employs some form of monitoringscheme, the required compensating changes in RF power input would be allbut impossible for a user to implement. Realistically, the only viablesolution would be to clean the chamber frequently, perhaps as often asafter the completion of each etch operation. However, this increase inthe frequency of cleaning (for example, over that necessary when etchingaluminum) would be unacceptable to most users as it would lowerthroughput rates and increase costs significantly.

Another drawback associated with a conventional inductively coupled etchreactor, such as the one depicted in FIG. 1, is that the structureplaces limitations on power deposition and etchant species diffusionwithin the chamber 10. Power deposition in an etch reactor's chamber 10concerns the distribution of power within the chamber's interior. Forexample, the regions 11 designated by dashed lines in FIG. 1, exhibit ahigh level of power deposition owing to their proximity to the coil 12.Whereas, the power deposition away from these regions 11, such as nearthe workpiece 14, is much lower. However, in many applications, it isdesirable that the region of the chamber immediately adjacent theexposed surface of the workpiece 14 exhibit a high power deposition. Forexample, a high power deposition near the exposed surface of theworkpiece 14 may be advantageously used to create a high plasma iondensity in that region. Granted, the shape of the chamber might bechanged to move the coil 12, and so the region of high power deposition,nearer to the workpiece 14. A variety of chamber shapes are known. Forexample, dome-shaped chambers are sometimes employed wherein the coilwraps around the outside also forming a dome shape. However, there arelimits to how the chamber can be shaped in an attempt to bring theregions of high power deposition to the most advantageous location inrelation to the workpiece. These limits derive from the fact that theshape of the chamber also has a significant impact on thecharacteristics of the plasma and the etch processing parametersassociated therewith. Thus, a compromise must be struck between theshape of the chamber and the desired power deposition pattern therein.Typically, this precludes optimizing the power deposition within thechamber.

The other factor mentioned above is etchant species diffusion. This termrefers to the tendency for etchant species to migrate from areas of highconcentrations, such as a region having a high power deposition wherethey tend to be formed in great quantities, to areas of lowerconcentrations. The diffusion patterns are dependent upon the particulartype of etchant species involved, and can vary significantly from one toanother. Thus, it is possible to influence the make-up of the plasmaadjacent the exposed surface of the workpiece 14 by tailoring the powerdeposition profile in the chamber to take advantage of the diffusioncharacteristics of the etchant species formed in the plasma.Consequently, it is still feasible to have regions 11 of high powerdeposition remote from the exposed surface of the workpiece 14, whilecreating the desired plasma characteristics in the region adjacent thissurface. However, a problem arises when the particular species that isdesired to be diffused to the region adjacent the workpiece 14 is of atype having a relatively short life span, so short that it no longerexists by the time mere diffusion processes would have brought it intothe region adjacent the workpiece. Again, employing a differently shapedchamber could assist in bringing the high power deposition regions 11closer to the workpiece 14, and thereby making it more likely thedesired short-lived etchant species reach the workpiece while stillviable. However, this reshaping must be balanced against the effect thechamber shape has on the plasma characteristics associated therewith. Ithas been found that the chamber cannot be reshaped to the extentnecessary to ensure many known short-lived etchant species are presentat the surface of the workpiece 14. For example, employing theconventional reactor configuration shown in FIG. 1, and a typicaletchant gas such as chlorine, short-lived species such as Cl⁺ and Cl₂ ⁺ions in excited states which are formed in the regions 11 of high powerdeposition will not diffuse into the region adjacent the workpiece 14prior to becoming extinct.

Yet another drawback associated with a conventional inductively coupledetch reactor, such as the one shown in FIG. 1, involves the cooling ofthe walls of the chamber 10. Etching processes are typically only stableand efficient if the chamber temperature is maintained within a narrowrange. However, formation of the plasma generates heat which can raisethe chamber temperature above the required narrow range. Consequently,it is desirable to remove heat from the chamber 10 in order to maintainthe optimum temperature range associated with the etch process beingperformed. As mentioned previously, this is typically done by flowingcoolant fluid through the cooling channels 32 formed within theconductive portion 34 of the chamber 10 and flowing air over theexterior of the insulative chamber walls 30. A problem arises in thatthe electrically insulative materials, such as quartz or ceramic,typically used to form the chamber walls also exhibit a low thermalconductivity. Thus, the chamber walls are thermally insulative and donot make an ideal heat transfer medium for picking up heat from theinterior of the chamber 10 and dumping it into the air flowing over theexterior of the walls. As a result, the chamber temperature tends tofluctuate more than is desired in the region adjacent the insulativechamber walls because the heat transfer from the chamber 10 is sluggish.Often the temperature fluctuations exceed the aforementioned narrowrange required for efficient etch processing. In addition, theseexcessive fluctuations can cause another problem. As discussedpreviously, etch by-products will tend to deposit on the chamber wallsduring the etch process. In attempting to control the chambertemperature by air cooling the insulative chamber walls 30, the chamberwall temperature and the layer of etch by-product formed on the interiorsurface thereof, tends to cycle. This cycling causes thermal stresseswithin the layer of etch by-product material which result in cracks andpieces of the material flaking off the wall and falling into thechamber. The loose deposit material can contaminate the workpiece, or itcan settle at the bottom of the chamber thereby requiring frequentchamber cleaning.

It is often desirable to inject etch process gas directly into theregions having the highest power deposition. In the conventional etchreactor shown in FIG. 1, these regions 11 are immediately adjacent thecoil 12. However, pathways to accommodate the gas injection ports 26cannot be formed in the chamber walls adjacent these areas of high powerdeposition without physically interfering with the induction coil 12.Thus, the gas has to be injected either in a void at the top of the coil12 or below the coil. Granted the flow of gas from these ports 26 can bedirected toward the regions 11 of high power deposition, but it is hasbeen found that this method is insufficient to ensure the optimumconcentration of etchant gas in these regions.

A conventional inductively coupled RF plasma etch reactor also must beoperated at relatively low pressures (e.g. below 100 mTorr) incomparison to a conventional capacitively couple etch reactor (which canoperated up to 10 Torr). Often etch processes will work best ifperformed at the higher pressures beyond the range of a conventionalinductively coupled plasma reactor. In addition, relatively high RFpower levels must be supplied to the coil antenna in order to overcomethe impedance created by the insulative chamber walls and still provideenough power to the chamber to ignite and sustain a plasma therein.Accordingly, a large-capacity RF power supply must be employed.

Accordingly, what is needed is an RF plasma etch reactor that isunaffected by conductive etch by-products which deposit on the interiorof the chamber. In addition, it is desirable that such an etch reactorbe capable of producing a self-bias voltage which will optimize the ionbombardment at the surface of the workpiece, as well as allowing thetailoring of the power deposition within the chamber without therestrictions imposed by the shape of the chamber walls. Further, theetch reactor would preferably have chamber walls which can be maintainedwithin a narrow temperature range which optimizes etch processing andprevents the flaking of deposits. It is also desirable that the gasinjection inlets be placeable anywhere on the chamber walls. Andfinally, the etch reactor would preferably be operable at pressures inexcess of about 100 mTorr and using an RF power level less than thatrequired to be supplied to the coil antenna of a conventionalinductively coupled RF plasma etch reactor.

SUMMARY

The stated objectives are realized by an RF plasma etch reactor havingan etch chamber with electrically conductive walls and a protectivelayer forming the portion of the walls facing the interior of thechamber. The protective layer prevents sputtering of material from thechamber walls by a plasma formed within the chamber. Absent thisprotective layer, sputtered material from the walls could degrade theetching process quality and contaminate the workpiece undergoing etch,thereby damaging the devices being formed thereon. Preferably, theelectrically conductive chamber walls are made of aluminum and theprotective layer is aluminum oxide (i.e. anodized aluminum). However,the protective layer could also be a conductive ceramic material, suchas boron carbide. The etch reactor also has an inductive coil antennadisposed within the etch chamber which is used to generate the plasma byinductive coupling. Like the chamber walls, the inductive coil antennais constructed to prevent sputtering of the material making up theantenna by the plasma. For example, the coil antenna could be madecompletely of a conductive ceramic such as boron carbide, or it could beconstructed so as to have a metal core (e.g. aluminum) with an outerjacket formed of a conductive ceramic material. In addition, the coilantenna could have a tubular structure with a hollow interior channel.This channel would be used to sustain a flow of coolant fluidtherethrough so as to cool the antenna and keep it within a prescribedtemperature range.

The above-described etch reactor has many advantages over conventionalinductively coupled plasma etch reactors. Since the inductive coilantenna is in the inside the etch chamber, rather than wrapped aroundits exterior, any conductive etch by-products which deposit on theinterior surfaces of the chamber walls will have no effect on the amountof power inductively coupled to the plasma. This, in combination withthe use of electrically grounded, conductive chamber walls which will bediscussed in detail later, prevents the unwanted changes in the plasmacharacteristics described previously. In addition, employing an internalinductive coil antenna resolves the issues concerning the shape andorientation of the antenna versus the shape of the chamber. The chambercan take on any advantageous shape (e.g. dome shape, cylindrical shape,truncated conical shape, or any combination thereof) without regard tothe aforementioned considerations of the coil antenna's shape andorientation, and the corresponding power deposition pattern within thechamber. Likewise, the coil antenna can take on any configuration (e.g.location, shape, orientation) that is necessary to achieve the desiredpower deposition pattern. As discussed previously, the desired powerdeposition pattern is one which provides optimum plasma characteristicsadjacent the surface of the workpiece undergoing etch processing withinthe chamber. These plasma characteristics include plasma ion density,plasma ion energy, ion directionality, and etchant species composition,among others. Examples of potential coil antenna configurations forachieving the desired power deposition pattern include constructing thecoil antenna with a unitary structure (i.e. one electrically continuousspirally wound conductor) supplied with RF power by a single source ofRF power, or constructing the antenna with a segmented structure. Thesegmented structure involves the use of at least two coil segmentswherein each segment is electrically isolated from the other segmentsand connected to a separate RF power signal. The individual powersignals can come from a single RF source with multiple adjustableoutputs, or plurality of separate adjustable RF sources. The unitarycoil antenna or each of the coil segments can have a planar shape, acylindrical shape, a truncated conical shape, a dome shape, or anycombination thereof. In addition, they can be oriented and locatedwithin the chamber as necessary to achieve the desired power depositionpattern.

Another advantage of an etch reactor constructed in accordance with thepresent invention involves the conductive chamber walls, such as onesmade of aluminum. Since the inductive coil antenna is located inside theetch chamber, there is no need to make the chamber from an insulativematerial, as is the case when the antenna is wrapped around the outsideof the chamber. A conductive material is chosen for the chamber wallsfor several reasons. First, the conductive walls can be electricallygrounded. In this way, the walls can serve as an electrical ground (i.e.anode) for the previously-described workpiece-supporting pedestal whichis connected to a source of RF power to create a bias voltage at thesurface of the workpiece. The interior surface area of the chamber wallswill greatly exceed the exterior surface area of the pedestal.Therefore, a larger negative bias voltage will result and a relativelystrong ion bombardment can be achieved, in comparison to conventionalinductively coupled plasma etch reactors. In addition, since the chamberwalls are already conductive, any conductive by-products from etchingprocesses performed in the reactor which deposit on the chamber wallswill not have a detrimental effect on the plasma characteristics. Forexample, there would be no sudden increase in the capacitive coupling ofRF power and ion energy caused by an electric coupling of the depositsto the grounded areas of the reactor which act as an anode for theenergized workpiece pedestal. Thus, the use of electrically groundedconductive chamber walls in combination with an internal inductive coilantenna ensures, that the plasma characteristic do not change even whenthe etch process results in conductive by-products coating the interiorwalls of the chamber.

Chamber walls made of a conductive metals such as aluminum would alsoexhibit significantly greater thermal conductivity than that ofconventionally employed electrically insulative materials such as quartzor ceramic. This results in a quicker transfer of heat from the interiorof the chamber to coolant fluid flowing through cooling channels formedin the chamber walls. Therefore, it is easier to maintain a narrowchamber temperature range and avoid the problems of a conventional etchreactor in connection with the cracking and flaking off of deposits fromthe chamber walls. Additionally, it is easier and less expensive to formcooling channels in aluminum chamber walls than in the conventionalquartz walls.

It is further envisioned that measures other than the location, shape,and orientation of the coil antenna or coil segments can be employed totailor the power deposition pattern within the etch chamber. Forexample, one or more electrically grounded shielding element(s) could beplaced between the antenna or antenna segments and the workpiece todecrease the amount of RF power inductively coupled to the region of theplasma beyond each shielding element. These shielding elements couldtake the form of an electrically grounded Faraday shield or conductivescreen. Alternatively, a magnetic field generator could be employed togenerate a blocking magnetic field within the chamber. The field wouldbe oriented so as to reduce the number of etchant gas ions formed by theplasma which are allowed to travel between the inductive coil antenna(or segments) and the workpiece. The field generator can include eithera permanent magnet or an electromagnet, and preferably has thecapability to vary the magnetic field generated so as to adjust thenumber of etchant gas ions allowed to travel between the inductive coilantenna (or segments) and the workpiece.

Another envisioned measure involves individually selecting the powerlevels of the RF power signals supplied to the coil segments (when used)to further tailor the power deposition pattern within the etch chamber.For example, an RF power signal exhibiting a higher power level suppliedto a particular coil segment would produce a region of higher powerdeposition adjacent that coil in comparison to regions adjacent othersimilarly configured segments supplied with an RF signal having a lowerpower level.

Yet another advantage of an etch reactor constructed in accordance withthe present invention concerns the flexibility with which etchant gasports or inlets can be placed in the chamber walls. In conventionalinductively coupled plasma etch reactors, the inductive coil antennaprecluded the incorporation of gas inlets on the portion of the chamberwalls adjacent to the externally wrapped coil. This is troublesomebecause it is often desirable to inject etchant gas into regions of highpower deposition, such as those formed immediately adjacent the coilantenna. Since the inductive coil antenna is disposed within the chamberof a reactor according to the present invention, this limitation in theplacement of etchant gas inlets no longer exist. Thus, the inlets can beplaced practically anywhere on the interior of the chamber walls,particularly in locations directly adjacent regions of high powerdeposition.

In addition to the above-described advantages of a plasma etch reactorconstructed in accordance with the present invention, it is pointed outthat the amount of RF power inductively and capacitively coupled intothe chamber can be varied by simply adjusting the amount of RF powersupplied to the inductive coil antenna (or segments) and the energizedpedestal. For example, a capacitively coupled plasma can be formed byproviding RF power solely to the pedestal (and/or the conductive chamberwalls). Conversely, a purely inductively coupled plasma can be formed byproviding RF power solely to the inductive coil antenna, or ifapplicable, to one or more of the independently powered coil segments.Or, the reactor can be operated using any desired mix of inductively andcapacitively coupled RF power. Thus, the reactor can operated in aninductively coupled mode, capacitively coupled mode, or a combined mode.This provides the opportunity to use the reactor to perform a variety ofetch operations over a wide process window.

In addition to the just described benefits, other objectives andadvantages of the present invention will become apparent from thedetailed description which follows hereinafter when taken in conjunctionwith the drawing figures which accompany it.

DESCRIPTION OF THE DRAWINGS

The specific features, aspects, and advantages of the present inventionwill become better understood with regard to the following description,appended claims, and accompanying drawings where:

FIG. 1 is a cross-sectional view of a conventional inductively coupledRF plasma etch reactor with a cylindrical chamber.

FIG. 2 is a cross-sectional view of an inductively coupled RF plasmaetch reactor with a dome-shaped chamber employing a cleaning electrode.

FIG. 3 is a cross-sectional view of an RF plasma etch reactorconstructed in accordance with the most preferred embodiment of thepresent invention.

FIGS. 4A-F are generalized cross-sectional views of RF plasma etchreactors constructed in accordance with the most preferred embodiment ofthe present invention employing electrically isolated, separatelypowered, inductive coil antenna segments.

FIGS. 5A-B are generalized cross-sectional views of RF plasma etchreactors constructed in accordance with the most preferred embodiment ofthe present invention employing electrically isolated, separatelypowered, inductive coil antenna segments and shielding elements.

FIG. 6 is a generalized cross-sectional view of an RF plasma etchreactor constructed in accordance with the most preferred embodiment ofthe present invention employing electrically isolated, separatelypowered, inductive coil antenna segments and a magnetic field generatorwhich produces a magnetic blocking field.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description of the preferred embodiments of the presentinvention, reference is made to the accompanying drawings which form apart hereof, and in which is shown by way of illustration specificembodiments in which the invention may be practiced. It is understoodthat other embodiments may be utilized and structural changes may bemade without departing from the scope of the present invention.

The problem of reduced inductive coupling of RF power into the chamberof a plasma etch reactor due to the build-up of conductive etchby-products on the interior walls of the chamber can be approached inseveral ways. For example, a self cleaning process can be employedwherein the chamber walls are cleaned of conductive deposits during theetch process itself. This self cleaning process involves the use of RFpowered electrodes which replace portions of the chamber walls. As shownin the reactor having a dome-shaped chamber 10′ and inductive coilantenna 12′ of FIG. 2, such an electrode 36 can be disposed at the topof the chamber 10′ in a central void located at the apex of the coil12′. The electrode 36 is energized via an RF power generator 38 througha matching network 40. The electrode 36 is energized via the generator38 at a low voltage during etch processing to keep conductive etchby-products from forming on the electrode 36 or immediately adjacentareas. This voltage would be low enough that the energized electrode 36does not significantly affect the etching process. However, the furtheraway from the electrode 36 that an area of the chamber wall is, the lessthe cleaning effect and the more likely conductive deposits will form.Therefore, to be effective, multiple electrodes would have to beemployed and placed close enough to each other that the entire interiorsurface of the chamber adjacent the coil is protected from the formationof conductive etch by-products. However, it has been found that theelectrode voltage has to be kept at such a low level, so as to notsubstantially affect the etch process, that electrodes merely placed atthe top and bottom of the coil 12′ are not sufficient to keep the entirechamber wall adjacent the coil 12′ free of deposits. Further, it is notpossible to place electrodes on the interior wall adjacent (i.e.directly underneath) the coil 12′ without interfering with the inductivecoupling of power in to the reactor chamber 10′. Accordingly, thisapproach, while reducing the problem, cannot completely eliminate it,and so is not as preferred as other approaches to be discussed later inthis specification.

Another approach to the conductive etch by-product deposit probleminvolves heating the chamber walls to a temperature above the depositiontemperature of the particular conductive etch by-product causing theproblem. However, this approach has drawbacks as well. The highestpractical temperature that the chamber wall of a typicalinductively-coupled etch reactor, such as the one depicted in FIG. 1,can be heated to is about 200 degrees Centigrade. Higher temperatureswould degrade the organic seals usually employed to seal the variousaccess points to the chamber. Some of the previously-described metalswhich are to be etched produce conductive by-products which havedeposition temperatures exceeding 200 degrees Centigrade. For example,the etching of both copper and platinum produce conductive by-productswith deposition temperatures exceeding approximately 600 degreesCentigrade. It might be possible to replace the typically used organicseals with ones made of metal. However, such metal seals are usuallyonly effective for one etch operation because they are susceptible tochanges in metallic structure or physical deformation at hightemperatures which would degrade their ability to seal the chamber. Forexample, a typical aluminum seal would deform at approximately 400degree Centigrade, and could not be reused. The need to replace theseals in the etch reactor after every etch operation would beunacceptable to most users. Thus, while this approach is useful when thedeposition temperature of the conductive etch by-product causing theattenuation of inductively coupled RF power is relatively low (e.g. lessthan about 400 degrees Centigrade if aluminum seals are employed), amore comprehensive solution is preferred.

FIG. 3 depicts an RF plasma etch reactor constructed in accordance withthe most preferred solution to the problem of reduced inductive couplingof RF power due to the build-up of conductive etch by-products on theinterior walls of the reactor chamber 10′″. Like conventionalinductively coupled plasma etch reactors (e.g. FIG. 1), there is avacuum chamber 10′″, a pedestal 16 for supporting a workpiece 14, a biasRF power generator 22 and associated impedance matching circuit 24 forimposing a RF bias on the workpiece 14, and a vacuum pump 28 to evacuatethe chamber 10′″ to a desired chamber pressure. However, the inductivecoil antenna 44 is quite different. Rather than being wrapped around theoutside of the reactor chamber 10′″, the coil 44 is disposed inside thechamber. This places the coil beyond any conductive etch by-productcoating on the interior walls of the chamber. Thus, the conductivecoating cannot attenuate the magnetic field generated by the energizedcoil 44 (or at least the portion directed into the plasma region of thechamber), and so there is no decrease in the inductive coupling of RFpower to this region. As a result, there is no detrimental effect on theplasma characteristics or difficulty in igniting and maintaining aplasma within the chamber. Of course, since the coil 44 is energizedduring etch processing, there will be no deposition of etch by-productsthereon which could interfere with the inductive coupling of power.Further, since the antenna is inside of the chamber it can generate aplasma using a lower level of RF power because the impedance of thechamber walls need not be overcome as is the case with a conventionalinductively coupled plasma etch reactor.

The interior coil 44 is shown in FIG. 3 as having a unitary, planarconfiguration and is disposed near the top of the chamber 10′″. Thisembodiment of the coil is unitary in that it is constructed from anelectrically continuous, spirally wound conductor. However, the coil canalternately take on a variety of shapes and locations within thechamber. In addition, the coil can be segmented, with the segments beingelectrically isolated and separately powered. FIGS. 4A-F are examples ofetch reactors employing these segmented, separately powered, interiorcoils. All these examples depict a coil having a first coil segment 46a-f and a second coil segment 48 a-f. The first coil segment 46 a-f isenergized via an external RF power source having a first RF powergenerator 50 a-f and first impedance matching network 52 a-f. The secondcoil segment 48 a-f is energized via an external RF power source havinga second RF power generator 54 a-f and second impedance matching network56 a-f. Separate power sources are shown supplying RF power to each ofthe coil segments 46 a-f, 48 a-f as well as the pedestal 16. This allowsthe amount of power, as well as the frequency to be individually set foreach of these elements. For example, different RF power levels orfrequencies may be applied to different coil segments by the separate RFpower generators connected thereto to adjust plasma ion density spatialdistribution. A common power source could also be employed for anynumber, or all, of the aforementioned elements if desired. Preferablythis common source would have the ability to supply RF power to theindividual elements at different power levels and frequencies. It isnoted that the number of turns of each coil segment implied by the theirillustration in FIGS. 4A-F (as well as the single coil of FIG. 3) is forrepresentational purposes only. The coil or coil segments may actuallyhave any number of turns.

As can be seen the primary difference between the reactors shown inFIGS. 4A-F, respectively, is the shape and location of the coil segments46 a-f, 48 a-f. In FIG. 4A, the first coil segment 46 a is planar inshape and is disposed near the top of the chamber 10′″, while the secondcoil segment 48 a is cylindrical in shape and located near the sidewalls of the chamber. In FIG. 4B, both coil segments 46 b, 48 b areplanar and located near the top of the chamber 10′″, with the firstsegment 46 b being concentric with and disposed within a central void ofthe second segment 48 b. FIG. 4C depicts a coil segment configurationmuch the same that of FIG. 4B, except the second coil segment 48 c islocated further down in the chamber closer to the workpiece 14. In thereactor of FIG. 4D, the first coil segment 46 d is planar in shape andis disposed near the top of the chamber 10′″, while the second coilsegment 48 d has an inverted, truncated, conical shape which is locatedso as to surround the workpiece 14. The reactors of FIGS. 4A-D are shownwith cylindrical shaped chambers 10′″. However, this need not be thecase. Since the inductive coil antenna resides inside the chamber 10′″,the shape of the chamber can be tailored to optimize its effect on theplasma. In other words, the shape of the coil is no longer a keyconsideration in the design of the chamber, therefore, the chamber canbe configured in any appropriate shape, preferably one which willenhance the particular plasma characteristic desired for the etchoperations to be performed with the reactor. For example, FIGS. 4E-Fdepict reactors with truncated conical shaped chambers 10′″. In FIG. 4E,the first coil segment 46 e is planar and disposed near the top of thechamber 10′″, while the second segment 48 e has a truncated, conicalshape and is located adjacent the side walls of the chamber 10′″. Thereactor of FIG. 4F is similar to that of FIG. 4E with the exception thatthe second coil segment 48 f has an inverted, truncated, conical shapeand is located further down in the chamber 10′″ nearer the workpiece 14.Of course, many other chamber shapes are possible, for example, thechamber could be dome shaped, or it could have an aggregate shapeincorporating two or more of the previously mentioned dome, cylindricaland truncated conical shapes. As the particular shape of the chamberwhich will optimize the desired plasma characteristics for a type ofetching being performed is beyond the scope of the present invention, nofurther details will be provided herein. Further, the inductive coilantenna or segments thereof can be disposed within the chamber by anyappropriate well known method, such as by mounting or suspending themfrom the chamber walls. As these methods are also well known and do notform a novel aspect of the present invention, no further details will beprovided.

FIGS. 4A-F depict inductive coil antennas having two individuallypowered coil segments. However, the present invention is not limited tojust two segment. Rather any number of individually powered segmentscould be employ. Further, like the shape of the chamber, the coil orcoils segments can take on any advantageous shape. As the inductive coilantenna is disposed inside the chamber 10′″, it can take on any shapedesired, independent of the shape of the chamber. Thus, the previouslydescribed tradeoff between the shape of the coil and the chamber is nolonger a concern. It is also noted that although only planar,cylindrical, and truncated conical shaped coil and coil segments aredepicted in FIGS. 3 and 4A-F, the present invention is not limited tothese shapes. Rather the coil or coil segments can have any advantageousshape, such as a dome shape or an aggregate of two or more of theaforementioned planar, dome, cylindrical and truncated conical shapes.In addition, it is not intended to imply that the location within thechamber where the coil or coil segments reside is limited the depictedembodiments. The coil or coil segments can be located and oriented inany advantageous configuration desired.

A significant advantage of placing the inductive coil antenna within thechamber is that, without the restrictions caused by the shape of thechamber, the power deposition can be optimized for the intended etchprocesses to be performed within the chamber. Placing the coil or coilsegments inside the chamber allow considerable flexibility in shapingthe power deposition. Such factors as the shape, location, andorientation of the coil or each coil segment can be chosen so as tocreate an optimal power deposition pattern within the chamber. Thesefactors can also be chosen in view of the expected diffusioncharacteristics and life spans of the etchant species involved in theparticular etch process envisioned for the reactor. Further, the amountof RF power supplied to the coil or coil segments can be varied totailor the power deposition and etchant species distributions, therebyallowing the same coil configuration to accommodate the diffusioncharacteristics of a wider range of etchant species types. The specificcoil or coil segment configuration and RF power input settings theretowhich will optimize the power deposition and etchant species diffusionfor the particular etch process to be performed is beyond the scope ofthe present invention. Accordingly these details will not be discussedherein.

In addition to the coil related factors such as shape, location, andorientation which can be manipulated in an effort to optimize the powerdeposition and etchant species diffusion patterns within the chamber,shielding elements or fields can also be introduced into the chamber tofurther tailor these patterns. For example, a shielding element or fieldcould be used to decrease the plasma ion energy in a particular regionof the chamber. FIGS. 5A-B (which correspond to the reactors describedin conjunction with FIGS. 4A-B, respectively) depict a shielding element58 a-b placed between one or more of the coil segments and the workpieceto affect the power deposition adjacent the element. This shieldingelement 58 a-b preferably takes the form a Faraday-type shield orconductive screen. In either case the shielding element 58 a-b iselectrically grounded. The grounded element 58 a-b attenuates themagnetic field generated by the adjacent coil segment or segments,thereby decreasing the inductive coupling of RF power to the plasma onthe other side of the shield. In this way the power distribution in theareas beyond the shielding element 58 a-b can be reduced as desired, forexample to decrease the plasma ion energy in the region. In FIG. 5A, acylindrical shielding element 58 a is employed adjacent the cylindricalsecond coil segment 48 a to reduce the RF power inductively coupled bythis segment to the plasma region in the center of the chamber 10′″.This is an example where only one of the coil segments is significantlyaffected. FIG. 5B illustrates an embodiment where the inductivelycoupled RF power from multiple coil segments (in this case two) isattenuated using a shielding element 58 b. The shielding element 58 b isplaced horizontally within the chamber below the first and second coilsegments 46 b, 48 b. This horizontal placement causes a reduction in theRF power inductively coupled by each segment 46 b, 48 b to the plasmaregion directly overlying the workpiece 14 on the opposite side of theshield element 58 b. Thus, the shielding element can be used to affectone or more, even all, of the coil segments employed in the reactor. Inaddition, more than one shielding element could be employed toaccomplish this task, if desired.

An alternative way of manipulating the power deposition is to introducesecond magnetic field into the chamber. As illustrated in FIG. 6, thiscan be accomplished by the addition of a magnetic field generator 60outside the chamber 10′″. The generator 60, which can include either anelectromagnet or a permanent magnet, creates a magnetic field within thechamber 10′″ which blocks the passage of ions. Thus, if the blockingmagnetic field is imposed between the inductive coil antenna 44 (orsegments thereof as would be the case in some embodiments of the presentinvention) and the workpiece 14, ions can be prevented from reaching theworkpiece. The stronger the magnetic field, the fewer ions that will beable to pass through and impact the surface of the workpiece. It ispreferred that the generator 60 be adjustable so as to vary the strengthof the blocking magnetic field. In this way the quantity of ions passingthrough to the workpiece 14 can be adjusted. Accordingly, plasmacharacteristics such as ion density and ion energy can be controlled atthe surface of the workpiece 14 by adjusting the strength of theblocking magnetic field.

Yet another advantage of placing the inductive coil antenna within thechamber is that the chamber need not be made of an insulative material.As explained previously, the portion of the chamber walls underlying theinductive coil antenna had to be made from a non-conductive material,typically quartz or ceramic, to prevent significant attenuation of themagnetic field generated by the coil which would decrease theinductively coupling of RF power into the chamber. With the coil insidethe chamber this problem is no longer a consideration. Therefore, thechamber walls can be made of conductive materials, such as aluminum.Making the chamber walls conductive has many desirable effects. First,as shown in FIG. 3, the chamber 10′″. can be electrically grounded andserve as the electrical ground for the RF power supplied through thepedestal 16. The surface area of the chamber walls is significantlygreater than the previously employed grounded areas. In addition, theinterior surface area of the now conductive and grounded chamber wallswill greatly exceed that of the RF energized pedestal 16. This willcreate a larger negative bias voltage, thereby making it feasible toproduce a more optimum plasma ion energy and directionality at thesurface of the workpiece.

Another advantage of employing conductive chamber walls is that itsolves the problem caused by the deposition of conductive by-productswherein the plasma characteristics (e.g. plasma ion energy anddirectionality) are adversely affected by the voltage shift thatoccurred when the conductive deposits electrically coupled with thegrounded areas of the chamber. Since the chamber walls are alreadyconductive and electrically grounded, the deposition of additionalconductive material on the interior surface of the walls is irrelevantand has no effect on the bias voltage or the plasma characteristics.

The final advantage that will be discussed in connection with the use ofconductive chamber walls is the enhanced cooling capability such wallscan afford. For example, chamber walls made of aluminum exhibit a muchhigher thermal conductivity in comparison to the quartz walls ofconventional inductively coupled plasma etch reactors (e.g. 204 W/mK foraluminum compared with 0.8 W/mK for quartz). In addition, as coolingchannels 32 are easily formed in aluminum chamber sidewalls and theentire chamber can now be made of aluminum, cooling channels can bedistributed throughout the chamber walls. This eliminates the need forair cooling the exterior of the chamber walls as was necessary with aconventional inductively coupled RF plasma etch reactor. Flowing coolantthrough internal cooling channels is a much more efficient method ofheat transfer. Consequently, heat transfer from the chamber interior tocoolant fluid flowing in the cooling channels 32 formed in the chamberwalls is much quicker. This increased rate of heat transfer allows formuch less variation in the chamber temperature. As a result, the chambertemperature can be readily maintained within that narrow range necessaryto ensure efficient etch processing and to prevent the cracking andflaking off of contaminating deposits from the chamber walls.

Conductive chamber walls made of metals such as aluminum can, however,have a potential drawback. These materials would tend to sputter undersome etch processing conditions. The material sputtered off of the wallscould contaminate the workpiece and damage the devices being formedthereon. This potential problem is prevented by forming a protectivecoating 45 over the interior surface of the chamber walls, as shown inFIG. 3. This coating 45 is designed to be resistant to the effects ofthe plasma and so prevents the conductive material from being sputteredinto the chamber 10′″. Further, the coating 45 is designed to have aninsignificant effect on the electrical and thermal properties exhibitedby the walls. If the chamber walls are aluminum, it is preferred theinterior surface be anodized (i.e. coated with a layer of aluminumoxide). The anodized aluminum layer will provide the protectivecharacteristics discussed above. Alternatively, a conductive ceramicmaterial could be chosen to coat the interior walls of the chamber toprevent sputtering and surface reaction on the walls. For example, boroncarbide would be an appropriate choice.

A similar sputtering problem exists with the inductive coil antenna orsegments described previously. If the coil or coil segments were to beformed of a metal, the unwanted sputtering of this metal by the plasmacould contaminate the workpiece, and would quickly erode the coilstructure. One solution is to make the coil or coil segments from a“non-sputtering” conductive material, such as a conductive ceramic likeboron carbide. Another possibility would be to use a metal coresurrounded by a “non-sputtering” coating. For example, an aluminum corecovered with a boron carbide jacket. In either embodiment, the coilwould be protected from the sputtering effects of the plasma and anycontamination of the workpiece prevented. It is also noted that thetemperature of the coil during etch processing must often be controlled.If such is the case, the coil can be constructed with a hollow,tube-like structure. This would allow coolant fluid to be pumped throughthe channel formed by the interior of the coil, thereby cooling the coiland maintaining the desired operating temperature.

Still another advantage of placing the inductive coil antenna within thechamber of an inductively couple plasma etch reactor is that the coil nolonger dictates where the etchant gas ports can be located. As explainedpreviously the etchant gas ports could not be located on the chamberwall adjacent an external inductive coil because the coil wouldphysically interfere with the necessary channeling and feed structuresneeded to supply such a gas injection port with etchant gas. This wasdisadvantageous because it is often desirable to introduce etchant gasinto a region of high power deposition, such as the ones formed justinside the chamber wall adjacent the external coil. Since the coil nolonger blocks access to the interior of the chamber through the chamberwalls, the locations where injection ports can be placed is increasedsignificantly. As a result, gas injection ports can be located so thatetchant gas is introduced near areas of high power deposition, or awayfrom these areas, as desired. For example, FIG. 3 shows gas injectionports 26 located adjacent the inductive coil antenna 44 such that theyare able to inject gas into areas 47 of high power deposition near thecoil antenna. Accordingly, there is a much greater versatility in portplacement possible with a reactor constructed in accordance with thepresent invention.

In addition to the advantages of an etch reactor constructed inaccordance with the present invention which have been described thusfar, it is also pointed out that the reactor could be operated in acapacitively coupled mode, in an inductively coupled mode, or anycombination thereof. Referring once again to FIGS. 3 and 4A-F, if RFpower is supplied to the pedestal 16, without also supplying RF powerthe coil antenna 44 or segments 46, 48, the reactor will operate in acapacitively coupled mode. This is not possible in a conventionalinductively coupled plasma etch reactor, such as shown in FIG. 1, due tothe previously-described inadequate area ratio between the pedestal 16and the conductive portion 34. The area ratios typically found inconventional reactors produce poor capacitive power coupling which hasbeen found insufficient to generate a plasma within the chamber.

Alternatively, RF power could be supplied to the coil antenna 44 orsegments 46, 48, without also supplying RF power the pedestal 16. Thus,the reactor would operate in an inductively coupled mode.

Inductive coupling will be more efficient at pressures ranging betweenabout 1 mTorr and 100 mTorr, while capacitive coupling will be moreefficient at pressures ranging between about 100 mTorr and 10 Torr. Someetch processes are best performed at lower pressures consistent withinductive coupling, whereas other etch processes are best performed atthe higher pressures consistent with capacitive coupling. Thus, areactor constructed in accordance with the present invention has agreater versatility than either a conventional inductively coupled orcapacitively coupled plasma etch reactor because it can support etchprocessing over much wider pressure ranges. Additionally, inductivecoupling will generate more ions, while capacitive coupling will producemore reactive neutral species. Different etching processes or processsteps often call for more ions or more reactive neutral species,depending on the desired result. A reactor constructed according to thepresent invention can control the composition of the plasma in ways notpossible with conventional inductively coupled or capacitively coupledetch reactors because the amount of RF power inductive and capacitivecoupled into the chamber 10 can be readily varied by varying the amountof power supplied to the pedestal 16 and internal coil antenna 44 (orantenna segments 46, 48). For example, some steps of an etch process canbe performed with more inductive coupling to create an ion-rich plasma,while other steps can be performed with more capacitive coupling tocreate a reactive neutrals-rich plasma. Further, the inductive coilantenna 44 (or segments 46, 48) need not be the only source employed tosustain the plasma. Rather, the plasma can be at least partiallysustained via capacitive coupling using the energized pedestal 16. Thisallows the RF power supplied to the antenna (or segments) to be tailoredto produce the desired etchant species concentrations without regard tothe power necessary to sustain the plasma.

While the invention has been described in detail by specific referenceto preferred embodiments, it is understood that variations andmodifications thereof may be made without departing from the true spiritand scope of the invention.

What is claimed is:
 1. A method for etching a workpiece held within anRF plasma etch reactor, comprising: employing an etch chamber havingchamber walls comprising a protective layer forming a portion of thewalls facing the interior of the etch chamber, said protective layerbeing capable of preventing sputtering of the chamber walls by a plasmaformed within the chamber; introducing an etchant gas into the interiorof the etch chamber; employing a conductive pedestal disposed within theetch chamber for holding the workpiece to be etched; and radiating RFenergy into the etchant gas to generate the plasma within the chamber byinductive coupling using an inductive coil antenna comprising aconductive non-sputtering material disposed within the etch chamber sothat the conductive non-sputtering material is exposed to the plasma. 2.The method of claim 1, further comprising the step of connecting thepedestal to a source of RF power so as to create a bias voltage at thesurface of the workpiece, said pedestal having an exterior surface areawhich is sufficiently smaller than that of the interior surface of thewalls of the etch chamber so that the bias voltage has a maximumpossible negative value.
 3. The method of claim 2, wherein the amount ofpower inductively coupled into the chamber is regulated by adjusting theamount of RF power supplied to the inductive coil antenna and the amountof power capacitively coupled into the chamber is regulated by adjustingthe amount of RF power supplied to the pedestal, said amount ofinductively coupled and capacitively coupled RF power being regulated totailor etchant species composition of the plasma and allow the reactorto be operated over a wide range of pressures, while still allowing forigniting and sustaining a plasma within the chamber.
 4. The method ofclaim 1, wherein the step of introducing the etchant gas comprisesintroducing the gas from inlets disposed on the interior of the walls ofthe etch chamber at locations closely adjacent regions within thechamber exhibiting a relatively high power deposition.
 5. A method foretching a workpiece held within an RF plasma etch reactor, comprising:employing an etch chamber having chamber walls; introducing an etchantgas into the interior of the etch chamber; and radiating RF energy intothe etchant gas to generate a plasma within the chamber by inductivecoupling using an inductive coil antenna with a unitary structuredisposed within the etch chamber, and wherein radiating RF energycomprises exposing conductive non-sputtering antenna material to theplasma.
 6. The method of claim 5, further comprising the step ofproducing prescribed plasma characteristics adjacent the surface of theworkpiece undergoing etching by creating a particular RF powerdeposition pattern within the chamber using a combination of thelocation, shape and orientation of the inductive coil antenna.
 7. Themethod of claim 6, wherein the step of creating the particular RF powerdeposition pattern within the chamber comprises using at least oneelectrically grounded shielding element capable of decreasing the amountof RF power inductively coupled from the inductive coil antenna to aregion of the plasma beyond each shielding element.
 8. The method ofclaim 6, wherein the step of creating the particular RF power depositionpattern within the chamber comprises generating a blocking magneticfield within the chamber oriented so as to reduce the number of etchantgas ions formed by the plasma traveling between the inductive coilantenna and the workpiece.
 9. The reactor of claim 8, further comprisingthe step of varying the blocking magnetic field so as to adjust thenumber of etchant gas ions allowed to travel between the inductive coilantenna and the workpiece.
 10. A method for etching a workpiece heldwithin an RF plasma etch reactor, comprising: employing an etch chamberhaving chamber walls; introducing an etchant gas into the interior ofthe etch chamber; and radiating RF energy into the etchant gas togenerate a plasma within the chamber by inductive coupling using aninductive coil antenna comprising a plurality of segments disposedwithin the etch chamber wherein each segment is electrically isolatedfrom the other segments and connected to a separate RF power signal, andwherein radiating RF energy comprises exposing conductive non-sputteringantenna material to the plasma.
 11. The method of claim 10, furthercomprising the step of producing prescribed plasma characteristicsadjacent the surface of the workpiece undergoing etching by creating aparticular RF power deposition pattern within the chamber using acombination of the location, shape and orientation of each segment ofthe inductive coil.
 12. The reactor of claim 11, wherein the step ofcreating the particular RF power deposition pattern within the chambercomprises individually setting levels of the RF power signals.
 13. Themethod of claim 11, wherein the step of creating the particular RF powerdeposition pattern within the chamber comprises using at least oneelectrically grounded shielding element capable of decreasing the amountof RF power inductively coupled from at least one of the segments of theinductive coil antenna to a region of the plasma beyond each shieldingelement.
 14. The method of claim 11, wherein the step of creating theparticular RF power deposition pattern within the chamber comprisesgenerating a blocking magnetic field within the chamber oriented so asto reduce the number of etchant gas ions formed by the plasma travelingbetween at least one of the inductive coil antenna segments and theworkpiece.
 15. The method of claim 14, further comprising the step ofvarying the blocking magnetic field so as to adjust the number ofetchant gas ions allowed to travel between the at least one inductivecoil antenna segments and the workpiece.
 16. A method for plasmaprocessing of a workpiece comprising generating a plasma within achamber using an antenna comprising a non-sputtering conductive materialsuch that the non-sputtering conductive material is exposed to theplasma.
 17. The method of claim 16 wherein generating the plasmacomprises using a coil antenna comprising conductive ceramic.
 18. Themethod of claim 17 wherein generating the plasma comprises using a coilantenna comprising boron carbide.
 19. The method of claim 16 whereingenerating the plasma comprises using a coil antenna comprising a corecomprising a metal and an outer jacket comprising a conductive ceramicmaterial.
 20. The method of claim 19 wherein generating the plasmacomprises using a coil antenna comprising a conductive ceramic materialcomprises boron carbide.
 21. The method of claim 16 wherein generatingthe plasma is generated with a coil antenna within conductive chamberwalls.
 22. The method of claim 21 wherein the plasma is generated withinconductive chamber walls comprising non-sputtering interior surfaces.23. The method of claim 22 wherein generating the plasma comprises usinga coil antenna comprising a conductive ceramic material.
 24. The methodof claim 16 wherein generating the plasma comprises using a coil antennadisposed adjacent a side wall of the chamber.
 25. The method of claim 24wherein generating the plasma comprises using a coil antennanon-conformal with the side wall.
 26. The method of claim 25 whereingenerating the plasma comprises using a coil antenna comprising aconductive ceramic material.
 27. The method of claim 26 wherein theplasma is generated within conductive chamber walls.
 28. The method ofclaim 27 wherein the plasma is generated within conductive chamber wallsfurther comprising non-sputtering interior surfaces.